Methods and apparatus for supporting multiple services in wireless communication system

ABSTRACT

The present disclosure relates to a communication technique of fusing a 5G communication system for supporting higher data transmission rate beyond a 4G system with IoT technology and a system thereof. The present disclosure may be applied to intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, health care, digital education, retail business, security and safety related service, or the like) based on the 5G communication technology and the IoT related technology. The present disclosure discloses a method and an apparatus for transmitting/receiving a random access channel (RACH) according to beam reciprocity (beam correspondence) with a method and an apparatus for supporting various services.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/721,620 filed on Sep. 29, 2017, which is related to and claimspriority to Korean Patent Application No. 10-2016-0125955 filed on Sep.29, 2016, and Korean Patent Application No. 10-2017-0045199 filed onApr. 7, 2017, the disclosures of which are herein incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relate to a wireless communication system, andmore particularly, to a method and an apparatus for supporting variousservices in a wireless communication system. Further, the presentdisclosure relates to a random access procedure design during abeamforming based initial access.

BACKGROUND

To meet a demand for radio data traffic that is on an increasing trendsince commercialization of a 4G communication system, efforts to developan improved 5G communication system or a pre-5G communication systemhave been conducted. For this reason, the 5G communication system or thepre-5G communication system is called a beyond 4G network communicationsystem or a post LTE system.

To achieve a high data transmission rate, the 5G communication system isconsidered to be implemented in a very high frequency (mmWave) band(e.g., like 60 GHz band). To relieve a path loss of a radio wave andincrease a transfer distance of the radio wave in the very highfrequency band, in the 5G communication system, beamforming, massiveMIMO, full dimensional MIMO (FD-MIMO), array antenna, analogbeam-forming, and large scale antenna technologies have been discussed.

Further, to improve a network of the system, in the 5G communicationsystem, technologies such as an evolved small cell, an advanced smallcell, a cloud radio access network (cloud RAN), an ultra-dense network,a device to device communication (D2D), a wireless backhaul, a movingnetwork, cooperative communication, coordinated multi-points (CoMP), andreception interference cancellation have been developed.

In addition to this, in the 5G system, hybrid FSK and QAM modulation(FQAM) and sliding window superposition coding (SWSC) that are anadvanced coding modulation (ACM) scheme and a filter bank multi carrier(FBMC), a non orthogonal multiple access (NOMA), and a sparse codemultiple access (SCMA) that are an advanced access technology, and so onhave been developed.

Meanwhile, the Internet is evolved from a human-centered connectionnetwork through which a human being generates and consumes informationto the Internet of Things (IoT) network that transmits/receivesinformation between distributed components such as things and processesthe information. The Internet of Everything (IoE) technology in whichthe big data processing technology, etc., is combined with the IoTtechnology by connection with a cloud server, etc., has also emerged. Toimplement the IoT, technology elements, such as a sensing technology,wired and wireless communication and network infrastructure, a serviceinterface technology, and a security technology, have been required.Recently, technologies such as a sensor network, machine to machine(M2M), and machine type communication (MTC) for connecting betweenthings has been researched. In the IoT environment, an intelligentInternet technology (IT) service that creates a new value in human lifeby collecting and analyzing data generated in the connected things maybe provided. The IoT may be applied to fields, such as a smart home, asmart building, a smart city, a smart car or a connected car, a smartgrid, health care, smart appliances, and an advanced healthcare service,by fusing and combining the existing information technology (IT) withvarious industries.

Therefore, various tries to apply the 5G communication system to the IoTnetwork have been conducted. For example, the 5G communicationtechnologies, such as the sensor network, the machine to machine (M2M),and the machine type communication (MTC), have been implemented bytechniques such as the beamforming, the MIMO, and the array antenna. Theapplication of the cloud radio access network (cloud RAN) as the bigdata processing technology described above may also be considered as anexample of the fusing of the 5G communication technology with the IoTtechnology.

SUMMARY

To address the above-discussed deficiencies, it is a primary object toprovide a method and an apparatus for efficiently operating a basestation and a terminal, if various services having differentnumerologies coexist in one system which is one of features of a 5Gcommunication system.

Another object of the present disclosure is directed to provision of amethod and an apparatus capable of efficiently performing a randomaccess procedure by receiving or determining, by a terminal, beamreciprocity (or beam correspondence) of a base station.

Objects of the present disclosure are not limited to the above-mentionedobjects. That is, other objects that are not mentioned may be obviouslyunderstood by those skilled in the art to which the present disclosurepertains from the following description.

Various embodiments of the present disclosure are directed to theprovision of a method of a terminal in a wireless communication system,including: receiving a synchronization signal from a base station; andreceiving a physical broadcasting channel (PBCH) using numerology usedfor a transmission of the synchronization signal among a plurality ofnumerologies that the terminal supports.

Various embodiments of the present disclosure are directed to theprovision of a terminal in a wireless communication system, including: atransceiver configured to transmit and receive a signal; and acontroller coupled with the transceiver and configured to receive asynchronization signal from a base station and to receive a physicalbroadcasting channel (PBCH) using numerology used for a transmission ofthe synchronization signal among a plurality of numerologies that theterminal supports.

Various embodiments of the present disclosure are directed to theprovision of a method of a base station in a wireless communicationsystem, including: transmitting a synchronization signal to a terminal;and transmitting a physical broadcasting channel (PBCH) using numerologyused for a transmission of the synchronization signal among a pluralityof numerologies that the terminal supports.

Various embodiments of the present disclosure are directed to theprovision of a base station in a wireless communication system,including: a transceiver configured to transmit and receive a signal;and a controller coupled with the transceiver and configured to transmita synchronization signal to a terminal and to transmit a physicalbroadcasting channel (PBCH) using numerology used for a transmission ofthe synchronization signal among a plurality of numerologies that theterminal supports.

Various embodiments of the present disclosure are directed to theprovision of a method of a terminal including: receiving information onbeam reciprocity from a base station; identifying a parameter fortransmitting a random access preamble form the information on the beamreciprocity; and transmitting the random access preamble to the basestation according to the confirmed parameter.

Various embodiments of the present disclosure are directed to theprovision of a terminal including: a transceiver configured to transmitand receive a signal; and a controller coupled with the transceiver andconfigured to receive information on beam reciprocity from a basestation, to identify a parameter for transmitting a random accesspreamble form the information on the beam reciprocity, and to transmitthe random access preamble to the base station according to theconfirmed parameter.

Various embodiments of the present disclosure are directed to theprovision of a method of a base station including: transmittinginformation on beam reciprocity to a terminal; and receiving a randomaccess preamble from the terminal according to a identified parameterfrom the information on the beam reciprocity.

Various embodiments of the present disclosure are directed to theprovision of a base station including: a transceiver configured totransmit and receive a signal; and a controller coupled with thetransceiver and configured to transmit information on beam reciprocityto a terminal and to receive a random access preamble from the terminalaccording to a identified parameter from the information on the beamreciprocity.

According to the present disclosure, the terminal can efficientlyreceive and transmit control information and data information in ascenario where various services having different requirements coexist.

In addition, according to the present disclosure, the terminal cantransmit the random access channel (RACH) by setting the RACHconfiguration to be different based on the information notifying whetherthe beam reciprocity (or beam correspondence) of the base stationincluded in the system information block (SIB) is established.

The effects that may be achieved by the embodiments of the presentdisclosure are not limited to the above-mentioned objects. That is,other effects that are not mentioned may be obviously understood bythose skilled in the art to which the present disclosure pertains fromthe following description.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1A illustrates a transmission of a synchronization channelaccording to an embodiment of the disclosure.

FIG. 1B illustrates a transmission of the synchronization channelaccording to an embodiment of the disclosure.

FIG. 1C illustrates a transmission of a synchronization channel and abroadcasting channel according to an embodiment of the disclosure.

FIG. 1D illustrates a procedure of a numerology information transmissionaccording to an embodiment of the disclosure.

FIG. 1E illustrates an operation of a base station for the numerologyinformation transmission according to an embodiment of the disclosure.

FIG. 1F illustrates an operation of a terminal for a numerologyinformation reception according to an embodiment of the disclosure.

FIG. 1G illustrates an operation of the base station for the numerologyinformation transmission according to an embodiment of the disclosure.

FIG. 1H illustrates an operation of the terminal for the numerologyinformation reception according to an embodiment of the disclosure.

FIG. 1I illustrates an operation of a base station for a numerologyinformation change according to an embodiment of the disclosure.

FIG. 1J illustrates an operation of a terminal for a numerologyinformation change according to an embodiment of the disclosure.

FIG. 1K illustrates a configuration of a terminal according to anembodiment of the disclosure.

FIG. 1L illustrates a configuration of a base station according to anembodiment of the disclosure.

FIG. 2A illustrates an RACH is transmitted in a specific frequencyresource and a specific subframe index.

FIG. 2B illustrates a RACH configuration information transmitted in anSIB.

FIG. 2C illustrates an RACH transmission when beam reciprocity isestablished.

FIG. 2D illustrates a RACH configuration information added to the SIBwhen the beam reciprocity of the base station is established.

FIG. 2E illustrates an RACH design when the beam reciprocity exists.

FIG. 2F illustrates an RACH configuration for using a plurality of RACHresources when the beam reciprocity of the base station is established.

FIG. 2G illustrates an RACH transmission when the beam reciprocity ofthe base station is not established.

FIG. 2H illustrates an RACH configuration including a beam operation ofthe base station.

FIG. 2I illustrates an RACH configuration including the beam operationof the base station.

FIG. 2J illustrates an RACH design when the beam reciprocity does notexist.

FIG. 2K illustrates a case where a data channel and a subcarrier spacingof the RACH are different.

FIG. 2L illustrates a case where the data channel and the subcarrierspacing of the RACH are the same.

FIG. 2M illustrates a method for notifying information, which notifieswhether the beam reciprocity of the base station is established, via anSIB.

FIG. 2N illustrates a method for notifying whether beam reciprocity of abase station is established.

FIG. 2O illustrates a method for notifying whether beam reciprocity of abase station is not established.

FIG. 2P illustrates a method for distinguishing an indication notifyingRACH configuration A (configuration in which beam reciprocity isassumed) or RACH configuration B (configuration in which beamreciprocity is not assumed) within the RACH configuration.

FIG. 2Q illustrates an operation of the RACH transmission of theterminal according to the beam reciprocity of the base station.

FIG. 2R illustrates an RACH operation method when considering one or aplurality of RACH formats.

FIG. 2S illustrates a case where a plurality of RACH formats A and RACHformats B are transmitted in one slot

FIG. 2T illustrates a method for supporting various Tx occasions.

FIG. 2U illustrates a structure of an RACH preamble format according toan embodiment of the disclosure.

FIG. 2V illustrates parameters of the RACH preamble format according toan embodiment of the disclosure.

FIG. 2W illustrates the configuration of the terminal according to theembodiment of the present disclosure.

FIG. 2X illustrates the configuration of the base station according toan embodiment of the disclosure.

DETAILED DESCRIPTION

FIGS. 1A through 2X, discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

Various advantages and features of the present disclosure and methodsaccomplishing the same will become apparent from the following detaileddescription of embodiments with reference to the accompanying drawings.However, the present disclosure is not limited to the embodimentsdisclosed herein but will be implemented in various forms. Theembodiments have made disclosure of the present disclosure complete andare provided so that those skilled in the art can easily understand thescope of the present disclosure. Therefore, the present disclosure willbe defined by the scope of the appended claims. Like reference numeralsthroughout the description denote like elements.

In this case, it may be understood that each block of processing flowcharts and combinations of the flow charts may be performed by computerprogram instructions. Since these computer program instructions may bemounted in processors for a general computer, a special computer, orother programmable data processing apparatuses, these instructionsexecuted by the processors for the computer or the other programmabledata processing apparatuses create means performing functions describedin block(s) of the flow charts. Since these computer programinstructions may also be stored in a computer usable or computerreadable memory of a computer or other programmable data processingapparatuses in order to implement the functions in a specific scheme,the computer program instructions stored in the computer usable orcomputer readable memory may also produce manufacturing articlesincluding instruction means performing the functions described inblock(s) of the flow charts. Since the computer program instructions mayalso be mounted on the computer or the other programmable dataprocessing apparatuses, the instructions performing a series ofoperation steps on the computer or the other programmable dataprocessing apparatuses to create processes executed by the computer tothereby execute the computer or the other programmable data processingapparatuses may also provide steps for performing the functionsdescribed in block(s) of the flow charts.

In addition, each block may indicate some of modules, segments, or codesincluding one or more executable instructions for executing a specificlogical function (s). Further, it is to be noted that functionsmentioned in the blocks occur regardless of a sequence in somealternative embodiments. For example, two blocks that are consecutivelyillustrated may be simultaneously performed in fact or be performed in areverse sequence depending on corresponding functions sometimes.

Here, the term ‘˜unit’ used in the present embodiment means software orhardware components such as FPGA and ASIC and the ‘˜unit’ performs anyroles. However, the meaning of the ‘˜unit’ is not limited to software orhardware. The ‘˜unit’ may be configured to be in a storage medium thatmay be addressed and may also be configured to reproduce one or moreprocessor. Accordingly, for example, the ‘˜unit’ includes componentssuch as software components, object oriented software components, classcomponents, and task components and processors, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuit, data, database, data structures, tables, arrays, andvariables. The functions provided in the components and the ‘˜units’ maybe combined with a smaller number of components and the ‘˜units’ or maybe further separated into additional components and ‘˜units’. Inaddition, the components and the ‘˜units’ may also be implemented toreproduce one or more CPUs within a device or a security multimediacard.

First Embodiment

Efforts to develop an improved 5G communication system after thecommercialization of the 4G communication system have been conducted.

The main feature of the 5G communication system is to support variousservice scenarios having different requirements compared to the 4Gcommunication system. Here, the requirements may mean latency, datarate, battery life, and the like.

For example, an enhanced mobile broadband (eMBB) service aims at a datatransmission rate that is 100 times or higher than that of the 4Gcommunication system and may be regarded as a service for supportingfast growing user data traffic. As another example, an ultra reliableand low latency (URLL) service aims at very high datatransmission/reception reliability and very low latency compared to 4Gcommunication system, and may be usefully used for services using anautonomous vehicle, an e-health, a drone, or the like. As anotherexample, a massive machine-type-communication (mMTC) service aims tosupport a larger number of device-to-device communications per singlearea than a 4G communication system, and is an evolved service of the 4GMTC such as smart metering.

In the 4G wireless communication system, various services may coexist.For example, a normal LTE cellular communication service, adevice-to-device (D2D) communication service, amachine-type-communication (MTC) service, and a multicast broadcastmultimedia service (MBMS) communication service, or the like maycoexist. A terminal supporting these different services basicallysupports a normal LTE cellular service for a synchronization procedurewith a base station and a system information acquisition. For example, aterminal supporting the D2D communication service performs a downlinksynchronization process with the base station and acquires master systeminformation (MIB), before acquiring system information (e.g., resourceallocation information or the like which is used for the D2D operation)associated with an D2D operation from the base station. In anotherexample, a terminal supporting an MBMS communication service performs adownlink synchronization process with the base station and acquires themaster system information (MIB), before acquiring system information(e.g., MBMS subframe information or the like) associated with an MBMSreception from the base station.

To support these different services, the conventional 4G system alwaysuses the same subcarrier spacing (15 kHz), a transmission bandwidth (72subcarriers: 1.08 MHz) having the same size, the same FFT Size (128 FFTSize) regardless of a bandwidth used in the 4G system, therebytransmitting a synchronization signal and the system information.Therefore, the terminal can receive the synchronization signal and thesystem information regardless of the service (for example, D2Dcommunication service, MBMS communication service or the like) supportedby the terminal

Unlike the 4G communication system mentioned above, the 5G communicationsystem may consider the use of different numerologies for each serviceto satisfy different requirements for each service. In this case, thenumerology may mean at least one of a subcarrier spacing, an orthogonalfrequency division multiplexing (OFDM) symbol length (or a singlecarrier-frequency division multiplexing (SC-FDM) symbol length), atransmission bandwidth, an FFT size, and a CP Length. For example, tosatisfy the short latency requirement, the URLLC service may usesubcarrier spacings (e.g., 30 kHz, 60 kHz) larger than the conventional4G communication system (use of a 15 kHz subcarrier spacing). At thistime, since the subcarrier spacing is doubled from 15 kHz to 30 kHz, theOFDM (or SC-FDM) symbol length may be reduced twice. Therefore, thelatency may be reduced by using a short symbol length in the URLLCservice.

The synchronization signal of the 4G communication system consists of aprimary synchronization signal (PSS) and a secondary synchronizationsignal (SSS). The PSS uses a Zadoff-Chu (ZC) sequence of length 63 andis transmitted via 62 subcarriers (one of 63 subcarriers is punctured bya DC subcarrier). Since the length of the sequence used for thesynchronization signal affects the detection performance of thesynchronization signal, to guarantee performance similar to the 4Gsynchronization signal, even the synchronization signal of the 5Gcommunication system may use the sequence having the same length (length63) or a length larger than that. However, because the subcarrierspacing has increased to 30 kHz, a two-fold transmission bandwidth isrequired for the sequence transmission of length 63 (i.e., doubled from1.08 MHz to 2.16 MHz). If a specific base station supports only theURLLC using a 30 kHz subcarrier spacing, the terminal needs to be ableto receive the synchronization signal and the system informationtransmitted through the 30 kHz subcarrier spacing.

On the other hand, the URLLC service may be supported using the samesubcarrier spacing (15 kHz) as that of the conventional 4G communicationsystem. For example, in the conventional 4G communication system, 1transmission time interval (TTI) is a scheduling unit. In the case ofthe normal CP, the 1 TTI means 1 subframe (or 1 slot consisting of 7symbols) consisting of 14 OFDM symbols (or SC-FDM symbols) and in caseof an extended CP, the 1 TTI means 1 subframe (or 1 slot consisting of 6symbols) consisting of 12 OFDM (or SC-FDM) symbols. To satisfy the shortlatency requirement of the URLLC service, a short TTI (e.g., 2 to 3symbols) using a smaller number of symbols, a slot (e.g., 14 symbols),or a mini-slot (e.g., 1 to 6 symbols) may be used. In such a scenario,the base station may transmit the synchronization signal and the systeminformation using the same numerology (e.g., 15 kHz subcarrier spacing)as the conventional 4G communication system. Therefore, the terminalneeds to be able to receive the synchronization signal and the systeminformation transmitted through the 15 kHz subcarrier spacing.

It may be determined which of numerologies the URLLC service will useaccording to a provider's preference and a coexistence scenario withother services. Therefore, the terminal supporting the URLLC serviceneeds to be able to receive the synchronization signal and the systeminformation that are transmitted using various numerologies for allpossible scenarios.

As another example of the use of various numerologies, in theconventional 4G communication system, a center carrier frequency domainranges from 700 MHz to 4 GHz, whereas in the 5G communication system,the center carrier frequency domain ranges from 700 MHz to 100 GHz foreMBB service support using a wide bandwidth (for example, 1 GHz). If thecenter carrier frequency is increasing (for example, 30 GHz, 60 GHz,etc.), a random frequency fluctuation occurring in a local oscillator ofthe base station and the terminal is increased, and thus phase noise isincreased. The phase noise causes a common phase error and aninter-carrier interference (ICI), which is a major cause ofdeterioration in performance of systems (e.g., WiGig operated at 60 GHz)operated at a high center carrier frequency. Therefore, to solve theproblem, a wide subcarrier spacing needs to be used if the centercarrier frequency is increasing. In order that performance of asynchronization signal of a 5G system (for example, 240 kHz) in which awide subcarrier spacing is used is designed to be similar to that of theconventional 4G communication system, as described above, the sequencelength of the synchronizing length used in the 5G system needs to besimilar to or longer than the conventional 4G communication system. Atthis time, since the 5G communication system operated in a highfrequency band uses a wide subcarrier spacing, it is necessary to use awider bandwidth for the transmission of the synchronization signal. Forexample, if the 5G communication system uses a sequence having the samelength as the 4G communication system, then the 5G communication systemrequires a transmission bandwidth 16 times larger than that of the 4Gcommunication system for the transmission of the synchronization signal(the 240 kHz subcarrier spacing is 16 times the 15 kHz subcarrierspacing).

On the other hand, in order to support the eMBB service requiring alarge bandwidth, carrier aggregation may be used. In such a scenario, asthe subcarrier spacing used for the transmission of the synchronizationsignal, 15 kHz which is the same as the conventional 4G communicationsystem may be used.

Therefore, even the terminal supporting the eMBB service needs to beable to receive the synchronization signal and the system informationthat are transmitted using various numerologies. In addition, in the 5Gcommunication system, various types of services using variousnumerologies may be defined without being limited to the above-describedembodiments. As described above, to support forward compatibility forservices which may be discussed in future, the terminal needs toflexibly support various numerologies.

Embodiments of the present disclosure to be described below will proposeconfigurations for solving the above-mentioned problem. In other words,in the scenario in which various services having different requirementswhich is one of the features of the 5G communication system uses variousnumerologies, a method for efficiently acquiring, by a terminal, asynchronization signal and system information, perform a random accessprocedure, and then transmitting/receiving uplink data and downlink datawill be described.

The present disclosure relates to a method of transmitting a downlinksynchronization signal and system information, a random access method,and a method for transmitting/receiving uplink and downlink data tosupport various numerologies when various numerologies which may besupported in the 5G communication system coexist. In addition, thepresent disclosure relates to a method and an apparatus for operating abase station and a terminal for transmitting/receiving signalstransmitted using various numerologies.

FIG. 1A illustrates a transmission of a synchronization channel (orsynchronization signal) according to an embodiment of the disclosure. Atthis case, the synchronization channel (or synchronization signal) maybe one synchronization signal consisting of one sequence or two or moresynchronization signals each consisting of two or more sequences. Inaddition, it is characterized that the synchronization channel consistsof one or two OFDM symbols.

For example, if the synchronization channel is two or moresynchronization signals consisting of two or more sequences, thesynchronization channel may consist of a primary synchronization signal(PSS) and a secondary synchronization signal (SSS) as in the LTE. ThePSS is generated as a Zadoff-Chu sequence and includes information on acell ID. The terminal acquires the information on the cell ID throughthe PSS detection and acquires timing information on asymbol/slot/subframe and information on a center carrier frequency ofthe system. On the other hand, the SSS is generated as an m-sequence andincludes information on a cell ID Group. The terminal acquires theinformation on the cell ID Group through an SSS detection and is used todetect a radio frame synchronization.

As another example, the synchronization channel may be threesynchronization signals consisting of two sequences. That is, thesynchronization channel may consist of the PSS, the SSS, and theextended synchronization signal (ESS). At this time, the sequence andpurpose of configuring the PSS and the SSS may be the same as theabove-mentioned examples. Meanwhile, the ESS consists of the ZC-sequencein the same way as the PSS. In the hybrid-beamforming system, the ESSmay include information on indexes of an orthogonal frequency divisionmultiplexing (OFDM) symbol or a single carrier-frequency divisionmultiplexing (SC-FDM) symbol.

As another example, the synchronization channel may be onesynchronization signal consisting of one sequence. That is, thesynchronization channel consists of one sequence like the PSS and mayinclude information on a cell ID, a sector ID, or a transmission andreception point (TRP) ID.

Meanwhile, in various cases described above, the synchronization channelmay be transmitted using various numerologies. At this time, thenumerology means at least one of a subcarrier spacing of thesynchronization signal, a cyclic prefix (CP) length of thesynchronization signal, a synchronization channel bandwidth of thesynchronous channel, and a fast Fourier transform size of thesynchronization signal. For example, in the system which supports acenter carrier frequency equal to or less than 6 GHz, the subcarrierspacing for the transmission of the synchronization channel may be 15kHz, 30 kHz, or 60 kHz. The CP length of the synchronization signal maybe either Normal CP or Extended CP. The transmission bandwidth of thesynchronization channel may be various like 180 kHz, 1.4 MHz, and 5 MHz.The FFT Size of the synchronization signal has relation to thetransmission bandwidth of the synchronization channel and the subcarrierspacing. For example, if 1.08 MHz is used as the transmission bandwidthat the 15 kHz subcarrier, a 128 FFT size may be used, and if 1.08 MHz isused as the transmission bandwidth at a 30 kHz subcarrier, a 64 FFT sizemay be used.

Graph (a) of FIG. 1A illustrates an example in which the synchronizationchannel is transmitted at the center carrier frequency of the system.Unlike this, graph (b) of FIG. 1A illustrates an example in which thesynchronization channel is transmitted in a region other than the centercarrier frequency of the system. Depending on the services (e.g. URLLC,eMBB, mMTC, etc.) that the system supports or depending on the carrier'spreferences and the center carrier frequency at which the system isoperated, the synchronization channel may be transmitted using variousnumerologies. In this way, if the synchronization channel is transmittedusing various numerologies, the terminal knows or needs to know theinformation on the numerology used for the transmission of thesynchronization channel to receive the synchronization channel.

More specifically, the information on the numerology for thetransmission of the synchronization channel may be mapped to thesequence used in the synchronization channel. In other words, thenumerology applied to the transmission of the synchronization channel(or synchronization signal) may be determined according to the sequenceused for generation of the synchronization channel (or synchronizationsignal). For example, if the synchronization channel consists of two ormore sequences, that is, if the synchronization signal is transmittedusing sequence A1, sequence A2, and sequence A3, the terminal may knowthat the system uses subcarrier spacing A (for example, 15 kHz, 30 kHz,60 kHz, etc.) based on the detection of the sequence A1. In addition,the terminal may know that the system uses the Normal CP based on thedetection of the sequence A2 and know that the system uses the extendedCP (CP having a length relatively longer than Normal CP) based on thedetection of the sequence A3. As another example, if the synchronizationchannel consists of two sequences of sequence B1 and sequence B2, theterminal may acquire the information on the subcarrier spacing based onthe detection of the sequence B1 and estimate the CP length in a blindway based on the sequence B2. In other words, the mapping relationshipbetween the sequence A1 and the subcarrier spacing A, the mappingrelationship between the sequence A2 and the normal CP, the mappingrelationship between the sequence A3 and the extended CP, the mappingrelationship between the sequence B1 and another subcarrier spacing, themapping relationship between the sequence B2 and the specific CP length,or the like may be predefined, and the base station and the terminal maypreviously share the mapping relationships. By the mapping relationship,the base station may implicitly notify the terminal of the informationon the specific numerology using the specific sequence, and the terminalmay know the information on the specific numerology from the sequence ofthe synchronization channel (or synchronization signal).

The normal CP length or the extended CP length used at differentsubcarrier spacings may be different. For example, the normal CP lengthused in the subcarrier spacing A and the normal CP length used in thesubcarrier spacing B may be different from each other. Similarly, theextended CP length used in the subcarrier spacing A and the extended CPlength used in the subcarrier spacing B may be different from eachother.

The transmission bandwidth of the synchronization channel may bedifferent for each system. For example, the bandwidth of thesynchronization channel used by the sequence A1 may be 1.08 MHz, and thebandwidth of the synchronization channel used by the sequence B1 may be2.16 MHz. At this time, the FFT size used for the transmission of thesequence A1 and the sequence B1 may be the same. As another example, thebandwidth of the synchronization channel used by the sequence A1 and thebandwidth of the synchronization channel used by the sequence B1 may bethe same (for example, 1.08 MHz). In this case, the FFT Size used forthe transmission of the sequence A1 and the sequence B1 may differentfrom each other (for example, 128 FFT in the case of the sequence A1 and64 FFT in the case of the sequence B1).

As another example of transmitting the information on the numerologyused for the transmission of the synchronization channel, theinformation on the specific numerology may be mapped to a transmissionposition of the synchronization channel. For example, if thesynchronization channel is transmitted at the center carrier frequencyof the system (1 a-2, 1 a-0) as illustrated in graph (a) FIG. 1A, theterminal recognizes that the numerology A (subcarrier spacing A1,transmission bandwidth A2 of the synchronization channel, FFT size A3,etc.) is used and performs the detection of the synchronization channel.On the other hand, if the synchronization channel 1 a-4 is transmittedin a region other than the center carrier frequency 1 a-3 of the systemas illustrated in graph (b) of FIG. 1A (1 a-6), the terminal recognizesthat the numerology B (subcarrier spacing B1, transmission bandwidth B2of the synchronization channel, FFT size B3, etc.) is used and performsthe detection of the synchronization channel. The mapping relationshipbetween the transmission region (or the transmission position on thefrequency axis) of the synchronization channel and the numerologyinformation is a value embedded in the base station and the terminal,and the terminal searches the synchronization channel using the embeddedvalue and acquires numerology information. If the synchronizationchannel consists of two or more synchronization signals, the terminaldetects one synchronization signal to acquire some (e.g., subcarrierspacing, bandwidth of the synchronization channel, FFT size, etc.) ofthe numerology information, the information is used for the detection ofthe remaining synchronization signals, and the remaining numerologyinformation (for example, CP length) may be acquired based on thedetection of the remaining synchronization signals.

FIG. 1B illustrates a transmission of the synchronization channelaccording to an embodiment of the disclosure. Unlike FIG. 1A, FIG. 1Billustrates an example in which one system transmits two or moresynchronization channels using different numerologies. A synchronizationchannel #1 1 b-1 transmitted at a frequency apart from the centercarrier frequency 1 b-0 by offset #1 1 b-3 may use the numerology 1 anda synchronization channel #2 1 b-4 transmitted at a frequency apart fromthe center carrier frequency 1 b-0 by offset #2 1 b-6 may use thenumerology 2. At this time, the numerology means one or at least one ofthe subcarrier spacing of the synchronization signal, the cyclic prefix(CP) length of the synchronization signal, the synchronization channelbandwidth of the synchronous channel, and the fast Fourier transformsize of the synchronization signal.

FIG. 1B illustrates that the synchronization channel #1 and thesynchronization channel #2 are transmitted at different frequencies atthe same time but they may be transmitted at different frequencies atdifferent times. For example, the synchronization channel #1 1 b-1 usingthe numerology 1 is transmitted at intervals of N1 ms at the centercarrier frequency or a frequency apart from the center carrier frequencyby the offset #1 1 b-3, and the synchronization channel #2 1 b-4 usingthe numerology 2 may be transmitted at intervals of N2 ms at a frequencyapart from the center carrier frequency by the offset #2 1 b-6. Morespecifically, the terminal performs synchronization through thesynchronization channel #1 1 b-1 transmitted at intervals of N1 ms andacquires information on the numerology 1. At this time, the base stationmay transmit an additional synchronization channel #2 1 b-4 in aUE-specific or cell-specific manner according to a request of theterminal. If the base station transmits the synchronization channel #2 1b-4 by the request of the terminal, the information on the numerology 2and the N2 ms information used in the synchronization channel #2 1 b-4may be signaled to the terminal in the UE-specific or the cell-specificmanner.

If a specific base station supports both of the mMTC and eMBB, since therequirements of the mMTC and the eMBB are different from each other, thenumerology used for the mMTC and the numerology used for the eMBB may bedifferent from each other. That is, the subcarrier spacing and thebandwidth for the mMTC service may be much smaller than the subcarrierspacing and the bandwidth for the eMBB service. Under the assumption,terminal A that wants to access the base station may support only themMTC service, and another terminal B may support only the eMBB service.The base station may transmit two or more synchronization channels usingdifferent numerologies so as to receive the synchronization channelbased on the numerology supported by each terminal. At this time, sincethe base station does not know whether a terminal supporting any servicetries to access, the base station may always transmit differentsynchronization channels using different numbers. In this case, a lot ofoverhead may occur due to the synchronization channel transmission.Accordingly, the base station may define a default numerology and alwaystransmit one synchronization channel using the default numerology (forexample, use the numerology 1 as the default numerology). At this time,when the terminal requests to perform transmission/reception of data andcontrol information using the numerology 2 after the base stationacquires information on whether or not the terminal supportingnumerology (for example, numerology 2) different from the numerology 1used by the base station is accessed (after capability negotiation) orafter an RRC connection setup, the base station may transmit theadditional synchronization channel #2. In other words, the base stationand the terminal may perform the initial access procedure by using aspecific default numerology and then transmit/receive additionalinformation on different numerologies according to the request orcommunication process of the terminal.

FIG. 1C illustrates a transmission of the synchronization channel andthe broadcasting channel according to an embodiment of the disclosure.Graphs (a) and (b) of FIG. 1C are diagrams illustrating an example inwhich the numerology used for the transmission of the synchronizationchannel is similarly applied even to a transmission of a physicalbroadcasting channel (PBCH). Unlike this, graphs (c) and (d) of FIG. 1Care diagrams illustrating an example in which the numerology used forthe transmission of the synchronization channel and the numerology usedfor the transmission of the broadcasting channel are different from eachother.

More specifically, as illustrated in graph (a) of FIG. 1C, asynchronization channel 1 c-1 and a broadcasting channel 1 c-2 aretransmitted at a center carrier frequency 1 c-0 of the system, and thesynchronization channel 1 c-1 and the broadcasting channel 1 c-2 may usethe same numerology. As another example, as illustrated in graph (b) ofFIG. 1C, a synchronization channel 1 c-5 and the broadcasting channelare transmitted in a region 1 c-8 other than a center carrier frequency1 c-4 of the system, and the synchronization channel 1 c-5 and thebroadcasting channel can use the same numerology (1 c-6, 1 c-7). At thistime, as described in FIG. 1A, the numerologies used in thesynchronization channel and the broadcasting channel may be identifiedby the terminal due to an offset difference between the center carrierfrequency of the system and the frequency at which the synchronizationchannel is transmitted. In other words, the numerologies used in thesynchronization channel and the broadcasting channel may be determinedby the transmission region (or transmission position) of thecorresponding channel.

Meanwhile, graphs (c) and (d) of FIG. 1C, if the numerology used in thesynchronization channel and the numerology used for the broadcastingchannel are different from each other, in order for the terminal todecode the broadcasting channel, the information on the numerology usedfor the broadcasting channel is required. As in graph (c) of FIG. 1C, ifa synchronization channel 1 c-10 and a broadcasting channel 1 c-11 aretransmitted (1 c-9, 1 c-14), some of the synchronization signalstransmitted to the synchronization channel 1 c-10 may provide theinformation on the numerology of the broadcasting channel 1 c-11. As ingraph (d) of FIG. 1C, if a synchronization channel 1 c-16 and abroadcasting channel 1 c-19 are transmitted through differentfrequencies (i.e., different offsets 1 c-18 and 1 c-21) within the samesystem bandwidth, offset values 1 c-18, 1 c-21, and 1 c-22 may includethe information on the numerology of the broadcasting channel. In otherwords, the offset values 1 c-18, 1 c-21, and 1 c-22 may indicate thenumerology of the broadcasting channel. For example, the information onthe numerology used for the broadcasting channel 1 c-19 may betransmitted through an offset (represented by offset 2 1 c-21 in graph(d) of FIG. 1C) value between a center carrier frequency 1 c-15 of thesystem and a frequency at which the broadcasting channel 1 c-19 istransmitted or an offset (represented by offset 3 1 c-22 in graph (d) ofFIG. 1C) value between the frequency at which the synchronizationchannel 1 c-16 is transmitted and the frequency at which thebroadcasting channel is transmitted. The offset value may be embedded inthe terminal or may be transmitted through one of the synchronizationsignals transmitted to the synchronization channel. That is, thesequence A of the synchronization signal 1 c-16 means a predeterminedoffset A, and the offset A may be mapped to the numerology A.

FIG. 1D illustrates a procedure of a numerology information transmissionbetween the base station and the terminal according to an embodiment ofthe disclosure. More specifically, if one system (base station) supportstwo or more different numerologies, the information on the numerologymay be transmitted in a downlink synchronization process and a systeminformation acquisition process as illustrated in graph (a) of FIG. 1D.Also, as illustrated in FIG. 1D, the numerology information may betransmitted in a random access procedure performed after the downlinksynchronization process and the system information acquisition process.After the random access procedure as illustrated in graph (c) of FIG. 1,the numerology information may be transmitted from the base station tothe terminal in the RRC connected state.

As illustrated in section (a) of FIG. 1D, if the numerology informationis transmitted in the downlink synchronization process and the systeminformation acquisition process, the numerology information may betransmitted according to the embodiments described with reference toFIGS. 1A, 1B, and 1C. That is, the terminal may acquire the numerologyinformation from a synchronization signal of the synchronization channeltransmitted from the base station that has performed the downlinksynchronization. At this time, the base station may set and operate thedefault numerology as follows.

First, the default numerology refers to the numerology used for thetransmission of the synchronization channel (or synchronization signal),and the terminal uses the default numerology before receiving separatesignaling for the change in the numerology from the base station. Inother words, the default numerology may refer to a predeterminednumerology used for the transmission of the synchronization channel (orsynchronization signal). According to the above-described embodiment,the default numerology may be determined according to a center carrierfrequency value (or an offset value from the system bandwidth) at whichthe synchronization channel (or synchronization signal) is transmitted.According to an example, if the terminal detects the synchronizationsignal from a sync roster, the terminal knows the default numerologyaccording to the center carrier frequency (or offset) of thesynchronization signal and uses the default numerology as the numerologyof the synchronization signal. Next, the terminal detects thebroadcasting channel through the default numerology. At this time, asillustrated in FIGS. 1A, 1B, and 1C, even if the center carrierfrequencies of the broadcasting channels and the transmission bandwidthsof the synchronization channels (synchronization signals) are different,the center carrier frequencies may be the same as each other. In otherwords, the broadcasting channel and the synchronization channel may betransmitted while the center carrier frequencies thereof being alignedwith each other.

More specifically, the terminal decodes a broadcasting channel usingnumerology information acquired through a synchronization channel 1 d-0received through the corresponding default numerology, and is operatedusing the acquired numerology information before there is separatesignaling from the base station. For example, if there is no separatesignaling for the change in the numerology, the terminal may apply anduse the same numerology (for example, default numerology) for atransmission of a system information block (SIB), a downlink controlchannel (physical downlink control channel (PDCCH)), a downlink datachannel (physical downlink shared channel (PDSCH)), a random accesschannel (physical random access channel (PRACH)), an uplink controlchannel (physical uplink control channel (PUCCH)), and an uplink datachannel (physical uplink shared channel (PUSCH)). If the base stationnotifies the terminal of the use of numerology different from thenumerology (i.e., default numerology) through the SIB, MIB orUE-specific RRC signaling, the terminal changes the numerology toreceive the downlink data/control information or transmit the uplinkdata/control information (1 d-1, 1 d-2).

As another example, the default numerology requests the terminal toallow the base station to change the numerology, and may be defined asnumerology which is used before receiving a response to the change inthe numerology from the base station (when the base station permits therequest of the terminal). The terminal uses the numerology informationacquired through the synchronization channel to transmit/receive alldata information and control information after the RRC connection setup.After the RRC connection setup, the terminal may request the terminal tochange the numerology (1 d-8), and may use numerology different from thedefault numerology when permitting the change (1 d-9).

The numerology used for the downlink transmitted from the base stationto the terminal and the numerology used for the uplink transmitted fromthe terminal to the base station may be different from each other. Inthis case, the numerology information used for the downlink may betransmitted to the terminal as illustrated in FIGS. 1A, 1B, and 1C, andthe numerology information used for the uplink may be transmitted fromthe base station to the terminal through the system information (MIB,SIB, remaining minimum system information (RMSI), or other systeminformation (OSI)).

In another example, the default numerology used by cell A and thedefault numerology used by cell B may be different from each other. Theterminal may acquire default numerology information of different cellsthrough the synchronization channel. However, this may increase a blinddetection frequency of the terminal for the numerology detection,thereby increasing power consumption of the terminal. Accordingly, aserving base station may transmit the cell ID of the neighboring basestations and the numerology information of the neighboring base stationsto the serving base station through the system information (SIB, RMSI,or OSI) or the UE-specific RRC signaling.

Meanwhile, as illustrated in section (b) of FIG. 1D, the numerologydifferent from the default numerology may be used in the random accessprocess (1 d-7). For example, if it is assumed that the numerology A isused in the downlink synchronization process and the system informationacquisition process, the terminal may perform a random access preambletransmission using numerology A′ (1 d-3). At this time, the numerologyA′ used for the random access preamble transmission may be the same asor different from the numerology A. If the numerology A′ and thenumerology A are different from each other, the information on thenumerology A′ is a value promised by the terminal and the base station,and may be a value embedded in the base station and the terminal. Asanother example, the information on the numerology A′ used for therandom access preamble transmission may be transmitted from the basestation to the terminal through the system information (i.e., MIB, SIB,RMSI or OSI).

After the terminal transmits the random access preamble to the basestation, the base station transmits a random access response (RAR) tothe terminal as a response thereto (1 d-4). At this time, the basestation may use the default numerology because it does not know thenumerology used by the terminal (in particular, the bandwidth that theterminal may support). For example, the mMTC terminal may support only asmall bandwidth (BW) compared to the eMBB terminal. As another example,the eMBB terminal A may support BW of 80 MHz, but another eMBB terminalB can support BW of 1 GHz. Since the base station does not know theinformation of the terminal, the base station needs to appropriatelydetermine the bandwidth of the downlink control channel (PDCCH) for RARtransmission and the downlink data channel (PDSCH) for RAR transmission.The bandwidth may be a minimum value embedded in the base station andthe terminal, or the base station may transmit the numerologyinformation including the BW through the system information (i.e., MIBor SIB). The terminal may acquire the numerology information for RARreception from the received system information and receive the RAR (1d-4).

In another example of section (b) of FIG. 1D, the terminal may transmitthe information on the numerology that the terminal may support to thebase station through Msg3 (1 d-5). In other words, it may be assumedthat the numerology (the synchronization channel and the broadcastingchannel and the numerology used for the RAR transmission) used beforethe Msg3 transmission uses the default numerology. More specifically,for example, the base station uses a 15 kHz subcarrier spacing, a normalCP length, a 1.4 MHz bandwidth, and a 128 FFT size for the transmissionof the synchronization channel, the broadcasting channel, and the RAR,and these parameters are values (a value embedded in the base stationand the terminal or a value acquired by the terminal through the MIB,SIB, RMSI, or OSI) promised between the base station and the terminal.The terminal may transmit information on the numerology that theterminal can support to the base station using the MAC layer information(MAC control element (CE) or MAC payload) or upper layer information(RRC information) when transmitting the Msg3 (1 d-5). The base stationreceiving the Msg3 acquires the information on the numerology that theterminal supports. The base station may transmit Msg4 to the terminal byapplying the numerology information acquired from the terminal throughMsg3 (1 d-6). As another example, the base station may transmit thecontrol information or the data information to the correspondingterminal by applying the numerology information acquired through theMsg3 after the RRC connection setup.

As illustrated in section (c) of FIG. 1D, after the RRC connectionsetup, the terminal may transmit the request for the change in thenumerator to the base station (1 d-8). For example, the base station mayintegrate a single synchronized channel, a broadcasting channel, andnumerology used for RAR and Msg4 transmission into one and use it. Theinformation on a numerology set that the base station may support may betransmitted to the terminal through the system information. Afteracquiring the system information, the terminal acquires the informationon the numerology that the base station may support, and determineswhether the numerology that the terminal may support is included in theinformation on the numerology set that the base station may support. Ifthe numerology that the terminal may support is included in thenumerology set that the base station may support, the terminal performsthe request for the change in the numerology (1 d-8). The request may betransmitted using the MAC layer information (MAC (control element) CE orMAC Payload) or the upper layer message (RRC) or may be transmitted tothe base station through L1 signaling (e.g., mapped to an uplink controlchannel or uplink reference signal). As the response to this, the basestation may inform the terminal whether the numerology has changedthrough the L1 Signaling (e.g., downlink control channel) (1 d-9).

FIG. 1E illustrates an operation of a base station for the numerologyinformation transmission according to an embodiment of the disclosure.More specifically, the case in which numerology information istransmitted through a synchronization signal transmitted through asynchronization channel is illustrated. The numerology information maybe mapped to the center carrier frequency used by the system or may bemapped to a frequency at which the synchronization channel istransmitted if the synchronization channel is transmitted in the regionother than the center carrier frequency that the system uses. Inaddition, if the synchronization channel is transmitted in the regionother than the center carrier frequency that the system uses, thenumerology information may be determined by the offset value between thecenter carrier frequency and the frequency at which the actualsynchronization channel is transmitted. The offset value may be mappedto the sequence of the synchronization signal transmitted to thesynchronization channel.

For example, in the system using the center carrier frequency A (e.g.,1.8 GHz), the synchronization signal may be transmitted at the centercarrier frequency A using the subcarrier spacing A (e.g., 15 kHz). Atthis time, the CP length used for the transmission of thesynchronization channel may be mapped to the sequence of thesynchronization signal or may be mapped to the position of thesynchronization signal. For example, if the sequence used for thesynchronization signal is a ZC sequence, the synchronization signal istransmitted in CP length A when a root index of the ZC sequence has an Avalue and the synchronization signal is transmitted in CP Length B whenthe root index of the ZC sequence has a B value. In this case, the CPLength B may be equal to the CP Length A, or the CP Length B may have avalue longer than the CP Length A. Information on whether the CP LengthB and the CP Length A use the same value or different values may beembedded in the base station and the terminal. As another example, theCP length is not mapped to the sequence but the terminal may detect itfrom the synchronization signal in a blind manner.

On the other hand, the bandwidth information used for the transmissionof the synchronization channel may vary according to the subcarrierspacing or may be the same regardless of the subcarrier spacing. Forexample, a system using 15 kHz at subcarrier spacings and a system using30 kHz may use a 1.4 MHz bandwidth for the synchronous channeltransmission. In this case, the system using 15 kHz and the system using30 kHz uses different number of subcarriers for the synchronizationchannel transmission. That is, in the system using 15 kHz, 72subcarriers and 128 FFT are used in the synchronization channeltransmission. In the system using 30 kHz, 36 subcarriers and 64 FFT areused in the synchronization channel transmission. On the other hand, thesame number of subcarriers may be used in the synchronization channeltransmission (e.g., 72) regardless of the subcarrier spacing. In thiscase, as the subcarrier spacing is changed, the bandwidth used for thetransmission of the synchronization channel may vary. In other words,the bandwidth may be scaled while the number of subcarriers (i.e., thenumber of tones) used for transmission of the synchronization channelremains the same.

If the numerology information is mapped to the difference (offset value)between the position of the frequency at which the synchronizationchannel is transmitted or the center carrier frequency and the frequencyat which the actual synchronization channel is transmitted, the terminalmay acquire the information on one or at least one of the subcarrierspacing, the CP length, the bandwidth of the synchronization channel,and the FFT size (1 e-1). The mapping information is a value embedded inthe terminal and the base station.

On the other hand, the information on the numerology may be transmittedto the terminal via the system information (MIB, SIB, RMSI or OSI) (1e-2, 1 e-3). In this example, the synchronization signal may use all thesame subcarrier spacings (e.g., 15 kHz may be equally used in the entirefrequency band) regardless of the center carrier frequency of the systemor use a specific subcarrier spacing at a specific center carrierfrequency (e.g., 15 kHz may be equally used in the center carrierfrequency band smaller than 6 GHz but the subcarrier spacing of 60 kHzmay be used in the center carrier frequency band larger than 6 GHz). Asanother example, the center carrier frequency at which the specificsubcarrier is used may be fixed. For example, 15 kHz may be used whenthe center carrier frequency is A, B, and C, 30 kHz may be used when thecenter carrier frequency is A, D, and E, and 60 kHz may be used when thecenter carrier frequency is A, F, and G. As another example, thenumerology used by the synchronization signal may be configured by thebase station regardless of the center carrier frequency that the systemuses. That is, the system A and the system B operated at a locationwhere a center carrier frequency is less than 6 GHz may use differentnumerologies, and the information thereon may be transmitted through thesynchronization signal by the method as described above or transmittedto the terminal through system information.

If the numerology information is transmitted to the terminal through thesystem information (MIB, SIB, RMSI, or OSI), the base station maytransmit another numerology information supported by its own cell. Forexample, the base station may transmit information on numerologies B andC in addition to the information on the numerology A supported by thebase station as follows.

- Supportable numerology = (numerology A, numerology B, numerology C) {numerology A = subcarrier spacing A1, CP length A2, BW = A3,...numerology B = subcarrier spacing B1, CP length B2, BW = B3,...numerology C = subcarrier spacing C1, CP length C2, BW = C3,... }

In addition, the base station may also include another numerologyinformation supported by a neighboring cell as well as its own cell. Forexample, the base station may transmit to the terminal the numerologyinformation on the base station of cell ID 2 together with thenumerology information on the base station of cell ID 1 as follows. Thisis to support the terminal to perform measurements on neighboring cells.That is, in order for the terminal to perform the measurement on theneighboring cell for the purpose of a periodic report or a handover, thenumerology of the neighboring cells should also be known in advance.Accordingly, the base station may notify the terminal of the numerologyinformation supported by the neighboring cells, thereby enabling theterminal to know which of the numerologies is used to perform themeasurement on the cell.

- Neighboring cell ID = (1, 18, 24, 109, 234, 310) { numerology set forcell ID 1 = (numerology A, numerology B, numerology C) { numerology A =subcarrier spacing A1, CP length A2, BW = A3,... numerology B =subcarrier spacing B1, CP length B2, BW = B3,... numerology C =subcarrier spacing C1, CP length C2, BW = C3,... } numerology set forcell ID 2 = (numerology A, numerology C, numerology D) { numerology A =subcarrier spacing A1, CP length A2, BW = A3,... numerology C =subcarrier spacing C1, CP length C2, BW = C3,... numerology D =subcarrier spacing D1, CP length D2, BW = D3,... } }

The numerology information of the neighboring cells may be transmittedcell-specifically through the SIB (or RMSI, OSI) or may be transmittedto a specific terminal through UE-specific RRC signaling.

Meanwhile, in the conventional 4G communication system, a system framenumber (SFN) of 10 bits is transmitted through the master informationblock (MIB). The SFN may have a value from 0 to 1023, and the role ofthe SFN is for allowing the terminal to match frame synchronization withthe base station. For example, if the base station sets the SFN of theMIB to be 124, the frame number of the system has a repeated value inorder of 0, 1, 2, . . . , 122, 123, 124, 0, 1, 2, . . . , 122, 123 . . .. Each system frame consists of 10 subframes in units of 10 ms.Therefore, in this example, if SFN=124, the actual subframe exists as1240 (1240 ms) within one system frame.

In the current LTE, the MIB is transmitted to the physical broadcastingchannel (PBCH), and the PBCH is transmitted every 10 ms. In this case,the MIB information transmitted to the PBCH is updated every 40 ms, andthe same MIB is transmitted within 40 ms (i.e., the same MIB istransmitted 4 times at 40 ms, and the terminal may combine them). On theother hand, the PBCH is transmitted in the 0-th subframe within a radioframe having a length of 10 ms radio consisting of 10 subframes.

On the other hand, if the numerology is changed according to theabove-mentioned various cases, the length of the subframe may bechanged. In this case, there may be two methods to determine thetransmission time of the MIB.

First, a method of determining the transmission time of the MIB using afixed time may be considered. In present embodiment, the transmissioncycle of the PBCH uses a fixed time (T1 ms). Even the transmission cycleof the MIB also uses a fixed time (T2 ms). This method is the same asLTE, and is operated independently of the numerology. For example, it isassumed that T1=10 ms and T2=40 ms. It is assumed that the numerologyinformation acquired by the terminal A through the synchronizationsignal of the cell A is subcarrier spacing=30 kHz and the numerologyinformation acquired by the terminal B through the synchronizationsignal of the cell B is subcarrier spacing=60 kHz. Since thetransmission cycle of the PBCH transmitted from each cell is fixed to beT1 ms and the transmission cycle of the MIB is fixed to be T2 ms, eachmobile station can receive the MIB by receiving the PBCH in thecorresponding cycle.

Next, a method of determining the transmission time of the MIB using afixed number of subframes (or a fixed number of slots) may also beconsidered. In present embodiment, the transmission cycle of the PBCHuses the fixed number of subframes (or the fixed number of slots) (N1).The transmission cycle of the MIB also uses the fixed number ofsubframes (N2). This method may be operated to make the transmissiontime of the PBCH different according to the numerology of PBCHtransmission time. For example, assume that N1=10 and N2=40. If thenumerology information acquired by the terminal A through thesynchronization signal of the cell A is subcarrier spacing=30 kHz, thecell A may a length of 1 subframe as 0.5 ms. If the numerologyinformation acquired by the terminal B through the synchronizationsignal of the cell B is subcarrier spacing=60 kHz, the cell B may alength of 1 subframe as 0.25 ms. Therefore, the terminal of the cell Acan determine that the PBCH is transmitted at a cycle of 5 ms (0.5ms×N1) in the A cell and that the MIB is transmitted at a cycle of 20 ms(0.5 ms×N2). In addition, the terminal of the cell B may determine thatthe PBCH is transmitted at a cycle of 2.5 ms (0.25 ms×N1) in the B celland that the MIB is transmitted at a cycle of 10 ms (0.5 ms×N2).

On the other hand, the numerology information may be transmitted througha UE-dedicated DL control channel (1 e-4). That is, the base station maynotify the numerology of the subframe that the terminal should usethrough the UE-dedicated DL control channel (e.g., PDCCH). For example,if the terminal A supports the URLLC and the terminal B supports theeMBB, the control information of the URLLC received by the terminal Aand the subcarrier spacing information (for example, 30 kHz) that thedata information uses may be transmitted through the PDCCH. At thistime, it may be assumed that the number of symbols used for the URLLCdata transmission is previously promised (for example, 7). That is, thebase station may notify the terminal of ‘00=15 kHz’, ‘10=30 kHz’, and‘11=60 kHz’ through 2 bits on the PDCCH. The terminal receiving theindication of 30 kHz (‘10’) decodes the URLLC data symbol based on theinformation (7 symbols). At this time, the URLLC terminal needs toperform PDCCH decoding to acquire the resource allocation information ofdata and the numerology information used for data. For this purpose, thenumerology information used in the PDCCH needs to be known. Therefore,the numerology used for the PDCCH decoding may be the numerologyinformation acquired from the synchronization signal or the informationacquired through the SIB or MIB.

FIG. 1F illustrates an operation of a terminal for a numerologyinformation reception according to an embodiment of the disclosure. Morespecifically, FIG. 1F illustrates the operation of the terminal when theinformation on numerology is transmitted through the system information.The base station transmits information on additional numerologydifferent from the numerology used for the synchronization signal byincluding the information on the additional numerology in the MIBinformation (1 f-1) and the terminal may decode the SIB using thenumerology information included in the MIB if the correspondingnumerology is the numerology for the SIB. After the SIB decoding, if theSIB information includes information on another numerology (1 f-2), theterminal may perform the RACH operation using the numerology informationincluded in the SIB information. If the additional numerologyinformation is not included in the SIB, the terminal may perform theRACH operation using the numerology information included in the MIB. Asanother example, the base station may transmit the information on theadditional numerology different from the numerology used for thesynchronization signal by including the information on the additionalnumerology in the MIB information, and there may be the case in whichthe corresponding numerology may not be the numerology for the SIB. Inthis case, the terminal may decode the SIB using the numerologyinformation acquired from the synchronization signal (1 f-0). On theother hand, the MIB information may not include the additionalnumerology information. Even in this case, the terminal uses thenumerology used in the synchronization channel for the SIB decoding.

After receiving the MIB, there may be the case where the SIB informationincludes the information on another numerology (1 f-2) and if thecorresponding numerology is the numerology related to the RACH operation(for example, the numerology for the RACH preamble transmission). Atthis time, the terminal may perform the RACH operation using thenumerology information included in the SIB information. If theadditional numerology information is not included in the SIB, theterminal may perform the RACH operation using the numerology informationincluded in the MIB or the RACH operation using the numerologyinformation acquired from the synchronization signal. Alternatively, thenumerology information may also be received from the base stationthrough the UE-dedicated DL control channel (e.g., PDCCH) (1 f-3), andthe terminal may also perform communication using the numerologyinformation acquired through the PDCCH decoding.

FIG. 1G illustrates an operation of the base station for the numerologyinformation transmission/reception according to an embodiment of thedisclosure. The base station may transmit parameters for the randomaccess through the MIB, SIB, RMSI or OSI (1 g-0). In this case, thenumerology information may be included in the parameters for the randomaccess. If the numerology information is not included in the parametersfor the random access, the terminal is operated according to thefollowing procedures 1 g-1 to 1 g-4, under the assumption that thenumerology used in the synchronization signal is used for the randomaccess.

The numerology information for the random access transmitted by the basestation may include a subcarrier spacing, a CP length, a random accesspreamble transmission BW, a RAR reception BW, and the like which areparameters for the random access preamble transmission of the terminal.Meanwhile, as illustrated in FIG. 1E, the terminal that acquires thenumerology information using the system information transmitted to thesynchronization channel or the broadcasting channel performs the randomaccess procedure. Before the random access procedure is completed, sincethe uplink synchronization process between the base station and theterminal is not performed, the base station acquires the information onthe numerology that the terminal can support. Therefore, the basestation may acquire the information on the numerology that the terminalcan support or that the terminal prefers (1 g-1, 1 g-2) through therandom access procedure. For example, suppose that terminal A supportsthe URLLC service. Since it is important that the URLLC servicesatisfies the delay requirement, it may be necessary to use thesubcarrier spacing A1 to satisfy the requirement. At this time, CPlength A2 may be used and bandwidth A3 may be used. On the other hand,suppose that the terminal B supports the mMTC service. Since it isimportant that the mMTC service satisfies the requirement of thetransmission distance, to satisfy this, it is possible to use asubcarrier spacing B1 (subcarrier spacing B1<subcarrier spacing A1),support a CP length B2, and use a bandwidth B3.

FIG. 1F illustrates an operation of a terminal for a numerologyinformation reception according to an embodiment of the disclosure. Theterminal may receive the parameter information for performing the randomaccess from the base station through the MIB, SIB, RMSI or OSI (1 h-0).At this time, the parameter information may include the information onthe numerology to be used in the random access. For example, thenumerology information (subcarrier spacing, CP length, random accesspreamble transmission BW, RAR reception BW, etc.) may be included. Theterminal may transmit the random access preamble using the numerologyinformation (1 h-0). The numerologies used for the RAR reception, theMsg3 transmission, and the Msg4 reception may be the same or differentaccording to on the values that the base station configures (1 h-1, 1h-2, 1 h-3).

If the MIB or the SIB does not include RACH numerology information forthe random access, the terminal transmits the random access preambleusing the fixed numerology, receives the RAR using the fixed numerology,and transmits the Msg3 and receives the Msg4 using the fixed numerologyto transmit Msg3 and receives Msg4 (1 h-0, 1 h-1, 1 h-2, 1 h-3). At thistime, the fixed numerology may be the same as or different from thenumerology used for the synchronization signal. In the case of differentthe numerology used in the synchronization signal, a separate mappingrule exists and the base station and the terminal uses a promised valueto each other. For example, if the numerology used in thesynchronization signal is A, the numerology transmitted to the randomaccess preamble may be A1, the numerology used for the RAR reception maybe A2, the numerology used for the Msg3 transmission and the Msg4reception may each be A3 and A4. At this time, A1, A2, A3 and A4 mayhave different values.

FIG. 1I illustrates an operation of a base station for a numerologyinformation change according to an embodiment of the disclosure. Thebase station may transmit numerology candidate set information of theserving base station or base station neighboring to the serving basestation to the terminal through the MIB, SIB, RMSI or OSI (1 i-0). Ifthe numerology supported by the terminal, the terminal is included inthe numerology candidate set transmitted by the base station, theterminal may transmit a numerology change request to the base station (1i-1). The base station receiving the numerology change request maytransmit a response to the numerology change request (1 i-2). Thenumerology change request transmitted from the base station to theterminal may be transmitted using the MAC layer information (MAC(control element) CE or MAC Payload) or the upper layer message (RRC) ormay be transmitted to the terminal through L signaling (e.g., mapped toa downlink control channel or a downlink reference signal).

FIG. 1J illustrates an operation of a terminal for a numerologyinformation change according to an embodiment of the disclosure. Theterminal may receive the numerology candidate set information of theserving base station or base station neighboring to the serving basestation to the terminal from the base station through the MIB, SIB, RMSIor OSI (1 j-0). If the numerology supported by the terminal, theterminal is included in the numerology candidate set transmitted by thebase station, the terminal may transmit a numerology change request tothe base station (1 j-1). The base station receiving the numerologychange request may transmit a response to the numerology change request(1 j-2). The request for the numerology change transmitted from theterminal to the base station may be transmitted using the MAC layerinformation (MAC (control element) CE or MAC Payload) or the upper layermessage (RRC) or may be transmitted to the base station through L1signaling (e.g., mapped to an uplink control channel or uplink referencesignal).

FIG. 1K illustrates a structure of a terminal according to an embodimentof the disclosure.

Referring to FIG. 1K, the terminal may include a transceiver 1 k-0, aterminal controller 1 k-1, and a storage unit 1 k-2. In the presentdisclosure, the terminal controller 1 k-1 may be defined as a circuit oran application specific integrated circuit or at least one processor.

The transceiver 1 k-0 may transmit/receive a signal to/from othernetwork entities. The transceiver 1 k-0 can receive, for example, thesynchronization signal, the system information, and the numerologyinformation from the base station.

The terminal controller 1 k-1 may control the overall operation of theterminal according to the embodiment of the present disclosure. Forexample, the terminal controller 1 k-1 may control the signal flowbetween the respective blocks to perform the operations according to theabove-described drawings and flowcharts. Specifically, the terminalcontroller 1 k-1 may be operated according to a control signal from thebase station, synchronize with the base station, communicate with thebase station, receive the numerology information for a specific service,and transmit/receive a message or a signal to and from other terminalsand/or the base station.

The storage unit 1 k-2 may store at least one of the informationtransmitted/received through the transceiver 1 k-0 and the informationgenerated through the terminal controller 1 k-1.

FIG. 1L illustrates a configuration of a base station according to anembodiment of the disclosure.

Referring to FIG. 1L, the base station may include a transceiver 1 l-0,a base station controller 1 l-1, and a storage unit 1 l-2. In thepresent disclosure, the base station controller 1 l-1 may be defined asa circuit or an application specific integrated circuit or at least oneprocessor.

The transceiver 1 l-0 may transmit and receive a signal to and fromother network entities. For example, the transceiver 1 l-0 may transmitthe synchronization signal and the system information to the terminal,and further may transmit the numerology information for a predeterminedservice.

The base station controller 1 l-1 may control the overall operation ofthe base station according to the embodiment of the present disclosure.For example, the base station controller 1 l-1 may control the signalflow between the respective blocks to perform the operations accordingto the above-described drawings and flowcharts. Specifically, the basestation controller 1 l-1 may not only transmit the synchronizationsignal and the system information for providing a service to theterminal, but also transmit the information on the predeterminednumerology to the terminal for the communication with the terminal.

The storage unit 1 l-2 may store at least one of the informationtransmitted/received through the transceiver 1 l-0 and the informationgenerated through the base station controller 1 l-1.

Second Embodiment

Hereinafter, a second embodiment will be described below.

The random access process, that is, the random access channel (RACH)transmission process based on beamforming can be designed inconsideration of the following matters.

-   -   1. The presence or absence of beam reciprocity (or beam        correspondence) should be considered.    -   2. The RACH sequence length should be reduced for the beam        change in the RACH transmission process.    -   3. Even if the beam is changed during RACH transmission, the        multiplexing with data channel should be performed.        Considering these requirements, the RACH procedure according to        the proposed embodiments may be designed as follows.

First, we assume that there is the beam reciprocity. The beamreciprocity means that a beam used when a terminal receives a specificsignal is used for transmission or the beam used for the transmissionmay be used for reception. That is, the beam reciprocity (or beamcorrespondence) means that the transmission beam of the base station (orthe reception beam of the terminal) at a specific time point may be usedas the reception beam (or the transmission beam of the terminal) of thebase station at another time point as it is.

The terminal performs a series of processes of adjusting downlinksynchronization with the base station according to the synchronizationsignal, and then transmits the RACH. At this time, the terminal mayselect an RACH preamble index according to the RACH configurationincluded in the system information illustrated in FIG. 2B, set thetransmission power, and transmit the RACH signal to the base station.Here, if assuming the beam reciprocity of the terminal, the terminal maytransmit the RACH by setting the transmission beam based on thereception beam used for the downlink synchronization. If other words, ifthere is beam reciprocity (or beam correspondence), the terminal maytransmit the RACH signal by setting the reception beam that has receivedthe synchronization signal as the transmission beam. In addition, ifassuming the beam reciprocity of the base station, the terminal mayassume the reception beam of the base station when the transmission beamof the base station that has transmitted the synchronization signal inthe downlink synchronization interval transmits the RACH. Therefore, theterminal may transmit the RACH using the RACH resource corresponding tothe beam by which the base station may receive the RACH transmitted fromthe terminal.

FIG. 2C illustrates the RACH transmission using the RACH resourceaccording to the beam of the base station when the beam reciprocity (orbeam correspondence) of the base station is established. In FIG. 2C, ifthe beam reciprocity (or beam correspondence) is established, atransmission beam 2 c-0 that the base station has used to transmit thesynchronization signal (or PBCH) is used as the reception beam forreceiving the RACH signal from the terminal (2 c-1). Similarly, theterminal uses the reception beam 2 c-0 used for receiving thesynchronization signal (or PBCH) as the transmission beam fortransmitting the RACH signal (2 c-1). Accordingly, since the terminalknows in advance by which of the reception beams the base stationreceives the RACH signal, the terminal transmits the RACH signal usingthe reception beam that has received the synchronization signal as itis. Meanwhile, in order to map the RACH resource to the reception beamof the base station, the transmission beam change order of the basestation and the reception beam change order of the base station shouldbe the same. The RACH signal is designed to be longer than a symbollength of a general data channel since a roundtrip delay should beconsidered. Therefore, the number of RACH signals that can betransmitted in one subframe is smaller than that of downlink signalsthat can be transmitted in one subframe. In order for the terminal todetermine the RACH resource, the total number of beams used by the basestation is required. FIG. 2D illustrates a method of notifying the SIBof the total number of beams used by a base station. Referring to FIG.2D, it can be seen that configuration information(PRACH-ConfigInfo-Withreciprocity) notifying the number of beams of thebase station is transmitted to the RACH configuration transmitted to theSIB when assuming the beam reciprocity. Here, the configurationinformation notifying the number of beams indicates the number of beamsoperated by the base station based on the number of subframes, and inFIG. 2D, N may be determined according to the operation of the basestation.

FIG. 2E illustrates a design example of an RACH signal when the beamreciprocity exists. As illustrated in FIG. 2E, the terminal maytransmit/receive the RACH signal using the RACH resource of an interval2 e-0 thickly indicated. One RACH resource consists of a cyclic prefix(CP), a guard period (GP), and an RACH symbol. The CP may be designedconsidering a propagation delay and a channel delay. Here, the GP isrequired for each RACH resource. The reason is that when the terminaltransmits the RACH signal using the neighboring resources, the GP isinserted to prevent an inter-subcarrier interference between subcarriersdue to different propagation delays.

In addition, the base station may repeatedly receive the RACH using aplurality of RACH resources in order to improve RACH receptionperformance. For this purpose, a parameter notifying for how many RACHresources the terminal should transmit the RACH signal as illustrated inFIG. 2F may be added to the system information. As illustrated in FIG.2F, the base station notifies, through a numberOfResources field,information indicating for how many resources the base station shouldtransmit the RACH signal to the terminal. Here, M is an integer greaterthan 1. The terminal receiving the RACH signal may transmit the RACHsignal to the base station repeatedly a predetermined number of times.Alternatively, the RACH preamble format may also be defined differentlydepending on how many times the RACH signal is repeated. The basestation may inform the terminal of the predetermined RACH format throughthe SIB.

Next, assume that there is no beam reciprocity (or beam correspondence).In this case, the terminal may not estimate the RACH resourcecorresponding to the reception beam of the base station as in the casein which there is the beam reciprocity. Therefore, the terminalcontinuously transmits the RACH signal within one subframe (or apredetermined time interval). At this time, since the base station maynot know by which reception beam the RACH signal of the terminal isreceived, the base station may receive the RACH signal while changingthe reception beam within the time interval. FIG. 2G illustrates theRACH transmission process when the beam reciprocity of the base stationis not established. As illustrated in FIG. 2G, even if the terminalestimates the most suitable transmission beam of the base station in thedownlink signal reception process (2 g-0), since it may not be assumedthat the beam may be used as the RACH signal reception beam of the basestation, the base station continuously transmits the RACH signal withina time interval (2 g-3) to receive the RACH signal while changing thereception beam (2 g-1, 2 g-2). For example, as illustrated in FIG. 2G,the terminal repeatedly transmits an n-th RACH signal using apredetermined transmission beam (2 g-1), and then repeatedly transmitsan n+1-th RACH signal using the next transmission beam (2 g-2). The basestation receives the RACH signal while changing the reception beam overthe time interval two times.

Since the terminal does not have information on the number of beams ofthe base station and how many beams are used in one subframe, thisinformation needs to be transmitted to the terminal with included in theSIB. FIG. 2H illustrates a RACH configuration information(prach-ConfigInfo_Withoutreciprocity) including information on a beamoperation of the base station in the absence of beam reciprocity (orbeam correspondence). As illustrated in FIG. 2H, the base station maynotify the RACH configuration information of the system informationabout how many reception beams the base station operates or notify forhow many subframe (or time interval) the terminal transmits the RACH bythe fixed beam.

FIG. 2I illustrates the RACH configuration information in the case wherethe beam operation of the base station is performed in units ofsubframes. According to the embodiment of FIG. 2I, since the beam of theterminal is changed in units of subframes, the beam operation of thebase station may not be efficient compared to the method illustrated inFIG. 2H but the amount of information included in the SIB may bereduced.

FIG. 2J illustrates a design example of an RACH signal when the beamreciprocity does not exist. As illustrated in FIG. 2J, the terminal maytransmit/receive the RACH signal using the RACH resource of an interval2 j-0 thickly indicated. In the embodiment of FIG. 2J, unlike FIG. 2E,the RACH resource that the terminal transmits does not include the CPand the GP but only transmits the RACH symbol. On the other hand, thebase station changes the reception beam with the concept of CP andreceives the RACH signal. In this case, since the RACH signal isrepeatedly received, the previously received RACH symbol serves as a CPof the RACH symbol consecutively received. In this way, the design ofthe RACH signal may vary according to the beam reciprocity of the basestation.

FIG. 2K illustrates a case where a data channel and a subcarrier spacingof the RACH are different. Referring to FIG. 2K, the base station mayreceive the RACH resource while changing the beam for the RACH reception(2 k-0). Here, in order to receive the RACH, the base station may filterRBs having N frequencies to receive only the RACH and then estimate theRACH while changing the beam (2 k-0), as in the conventional LTE method.However, since it is very difficult to use pass-band filtering toreceive the data channel, the FFT is performed by the length of the datasymbol. In this case, even if the data symbol and the RACH are allocatedat different positions in the frequency domain, the orthogonalitybetween the two channels is not established, resulting in the intercarrier interference (ICI). Therefore, a guard subcarrier is required toreduce the ICI.

FIG. 2L illustrates a case where the data channel and the subcarrierspacing of the RACH are the same. The RACH reception and data decodingprocess in FIG. 2L is similar to or similar to the process described inFIG. 2K. However, in the case of FIG. 2L, since the orthogonality of theRACH channel is maintained even if the data symbol is subjected to theFFT, the ICI does not occur. Therefore, it is advantageous to set thesubcarrier spacing of the RACH based on the beamforming to be the sameas the subcarrier spacing of the data channel. According to theembodiment, the base station may receive the RACH signal transmittedfrom the terminal while changing the reception beam (2 l-0, 2 l-1, 2l-2, . . . , 2 l-3, 2 l-4).

Hereinafter, the embodiments in which the base station notifies theterminal of the information on the beam reciprocity (or beamcorrespondence) described above will be described. The base station maytransmit a 1-bit signal notifying whether the beam reciprocity of thebase station is established as illustrated in FIG. 2M by adding the1-bit signal to the SIB. Alternatively, the base station may inform theterminal of the information indicating whether the beam reciprocity isestablished through the RACH configuration transmission.

When the beam reciprocity is established according to the embodimentillustrated in FIG. 2M, the base station may transmit the configurationinformation for beam reciprocity to the terminal as illustrated in FIG.2N. On the other hand, when the beam reciprocity is not establishedaccording to the embodiment illustrated in FIG. 2M, the base station maytransmit the configuration information for the case in which the beamreciprocity is not established to the terminal as illustrated in FIG.20.

Meanwhile, according to the embodiment illustrated in FIG. 2M, theterminal may transmit the RACH signal to the base station by setting theRACH configuration differently through the information notifying whetherthe beam reciprocity of the base station included in the SIB isestablished. A 1 bit indicator (ParameterInfo in FIG. 2P) that notifiesthe terminal of the beam reciprocity is included in the PRACH ConfigInfoto be able to indicate parameters depending on two configurations,respectively. FIG. 2P is a diagram illustrating a method in which theabove-mentioned 1-bit indicator (ParameterInfo) is included in the PRACHconfiginfo to indicate two configurations (configuration informationwhen ParameterInfo=0 or configuration information when ParameterInfo=1),respectively.

Also, the terminal may also know the beam reciprocity using an implicitmethod other than the explicit method using the 1-bit indicatordescribed above. That is, the RACH configuration described above mayhave different lengths depending on whether the beam reciprocity of thebase station is established. In this case, the terminal may assume twoSIB lengths (N1, N2), where N1 may indicate the SIB length when beamreciprocity is assumed, and N2 may mean the SIB length when the beamreciprocity is not established. At this time, the terminal may performthe blind detect on the SIB lengths corresponding to the lengths of N1and N2, respectively. The terminal knows the RACH configurationaccording to the length of the N1 or N2 that succeeds in the decodingand may transmit the corresponding RACH signal to the base stationaccording to the embodiment described in FIG. 2E (assumption of the beamreciprocity) or FIG. 2J (no assumption of the beam reciprocity).

As another embodiment, the base station may transmit the beamreciprocity of the base station to the terminal through the downlinksynchronization signal. That is, if the number of sequence sets of thedownlink synchronization signal is defined as Q, the sequence of Q/2 isallocated as the sequence when assuming beam reciprocity, and theremaining Q/2 sequences may be transmitted to the terminal by beingallocating as the sequence when not assuming the beam reciprocity. Thatis, from which sequence set the sequence is set may mapped to the beamreciprocity (or beam correspondence) to generate the synchronizationsignal. In this case, the complexity when the terminal performs thedownlink synchronization is doubled, but there is an advantage in thatthe overhead for inserting the 1-bit indicator or the blind detectiondepending on the length of the SIB is not performed.

FIG. 2Q illustrates an operation of the terminal for the above-describedprocess. In step 2 q-0 of FIG. 2Q, the terminal determines beamreciprocity capability of the base station. The process may apply atleast one of the explicit method for notifying, by a base station, beamreciprocity using a 1-bit indicator and the implicit method forperforming, by a terminal, a blind detection on different SIB lengths ordetermining beam reciprocity using a sequence of a synchronizationchannel. The terminal determines the beam reciprocity of the basestation, and if there is the beam reciprocity (or beam correspondence),receives an RACH configuration set A (2 q-2) or if there is no beamreciprocity (or beam correspondence), may receive an RACH configurationsset B. If receiving Set A (2 q-2), the terminal transmits the RACHsignal as illustrated in FIG. 2E. At this time, the power consumption ofthe terminal may be minimized (2 q-3). If receiving Set B (2 q-4), theterminal transmits a RACH signal as illustrated in FIG. 2J. At thistime, the terminal continuously transmits the RACH symbol instead of theGP so as to perform as much beam sweeping as possible (2 q-5). In thiscase, the base station may inform the terminal of how many RACHsubframes the terminal should transmit using the fixed transmission beamthrough the RACH configuration.

In the above-described embodiment, the method of explicitly orimplicitly notifying, by a terminal, beam reciprocity (or the beamcorrespondence) is describe, but the present disclosure is not limitedthese embodiments. That is, the base station may notify the terminal ofa predetermined RACH preamble format A or RACH preamble format B withoutnotifying beam reciprocity (beam correspondence). The RACH preambleformat A or B may be information indicating by which of the numerologythe terminal transmits the RACH. The terminal may transmit the RACHsignal according to the received RACH preamble format regardless ofwhether the terminal knows the beam reciprocity (beam correspondence) ofthe base station. At this time, if assuming that the plurality of RACHformats are transmitted, the RACH format A and RACH format B may beoperated as illustrated in FIG. 2R.

FIG. 2R illustrates an RACH operation method when considering one or aplurality of RACH formats.

In the example illustrated in FIG. 2R, the RACH format A is a formatwhen the beam reciprocity (beam correspondence) is established, and theRACH format B is a format when the beam reciprocity (beamcorrespondence) is not established. The format A may mean a format inwhich GT is not required between the RACH formats because the terminalselects a specific resource to transmit the RACH. That is, the GT is notrequired between the RACH formats A before the terminal transmits orreceives the data channel, and the GT is required to prevent the intersymbol interference before transmitting or receiving the data channel (2r-1). Since the format B does not consider the beam reciprocity (beamcorrespondence), the GT is required between the RACH formats Bregardless of the data channel (2 r-2, 2 r-3, 2 r-4).

In view of such an operation, a plurality of RACH formats can berepresented as illustrated in FIG. 2S. FIG. 2S illustrates a case wherea plurality of RACH formats A and RACH formats B are transmitted in oneslot.

In case of applying only the format A only as in FIG. 2S, since there isno GT, the last symbol is used as GT (2 s-1). When only the format B isapplied, the GT is inserted between RACH formats as illustrated in FIG.2R, which causes the interference in the data decoding when the data andthe RACH are FDM. Therefore, the format B may be allocated to the end ofthe RACH format (2 s-2). That is, if the format B is allocated, only theformat B is used in a slot (case illustrated at the bottom of FIG. 2S),or the format B is positioned at the end of the slot as illustrated inthe middle of FIG. 2s (2 u-2).

According to another embodiment of the present disclosure, the presentdisclosure described below may be applied.

A length of the above-described RACH preamble format may be very longaccording to the repeating (or, iterative) transmission frequency. Thatis, the length may be extended to the preamble length of (N×M) timesaccording to M depending on the repeating transmission N and the numberof Rx beams of the base station for the reliable transmission. In thiscase, the downlink scheduling constraints of the base station occursbecause the uplink resource needs to be reserved for a long time.Therefore, the base station should notify the terminal in IDLEmode/CONNECTED of the number of Tx occasions of the terminal through theRACH configuration or the MIB. The Tx occasion means the transmission ofthe RACH preamble format of the terminal and otherwise may be referredto as RACH Burst. The terminal transmits the RACH preamble format duringthe Tx occasion according to the request of the base station and may fixor change the transmission beam of the terminal during several Txoccasions. The base station may ideally change and receive a total of Nreceive beams during each Tx occasion, and needs to notify the terminalof M repeating transmissions to receive beams of a total of (N×M) times.

FIG. 2T illustrates the operations of the terminal and the base stationaccording to the Tx occasion. Case 1 illustrated at the upper part ofFIG. 2T shows a case where one Tx occasion (2 t-1) is considered in theTx occasion set (2 t-0). Here, it can be seen that the length of thepreamble format becomes very long according to the number of beams ofthe base station (2 t-2). Therefore, the DL scheduling constraint of thebase station occurs.

Meanwhile, in Case 2 illustrated in the lower part of FIG. 2T, in orderto alleviate the constraint, the base station notifies the terminal ofthe Tx occasions of a total of M times within the Tx occasion set (2t-4), and thus the terminal may be allocated the Tx occasion a total ofM times. Here, the terminal can transmit the transmission beam whilefixing or changing the transmission beam of the terminal during the Txoccasion of a total of M times. The RAR (MSG2) may be transmitted everyTx occasion (2 t-7) or may be transmitted after the Tx occasion of atotal of M times (2 t-6). If the base station transmits the RARnotifying fail following the Tx occasion interval in which the terminalfixes the transmission beam and transmits the RACH, the terminal changesthe transmission beam and may transmit the RACH signal in the next Txoccasion interval.

The length of the preamble format described above may be determinedaccording to the configuration of the base station, that is, it isdetermined by being allocated the iteration of N times and the Txoccasion of M times. Specifically, the length of the RACH preambleformat may be determined as follows.

-   -   1. Preamble format is that CP+(preamble length (seq)*N)+GT        length is repeated M times    -   2. It may be made in the form of PCP+(seq*N*M)+GT

Alternatively, similar to the table on the preamble format defined inthe LTE, the length of the RACH preamble format may be defined in theform of the table. That is, the repeating number on N may be previouslydefined in Table. The table illustrated in FIG. 2V illustrates anexample of the table defining the parameters associated with the RACHpreamble format. In FIG. 2V, the preamble format A represents a preambleformat (2 v-0) when there is the beam reciprocity (beam correspondence),and the preamble format B represents the preamble format (2 v-1) whenthere is no beam reciprocity. FIG. 2U is a diagram illustrating anexample of the RACH preamble format structure according to theparameters illustrated in FIG. 2V. According to the proposedembodiments, the RACH preamble format is defined using the samenumerology as the data channel, and the numerology for the RACH preambleformat may be transmitted to the terminal through the SIB, the remainingminimum system information (RMSI), and/or the other system information(OSI) for transmitting the system information. In FIG. 2U, 2 u-0 and 2u-1 each correspond to parameters 2 v-0 and 2 v-1 defined in FIG. 2V.Furthermore, a vacant space 2 u-3 in the 2 u-1 showing the case wherethere is no beam reciprocity (beam correspondence) may mean the GP.

FIG. 2W illustrates the structure of the terminal according to theembodiment of the present embodiment.

Referring to FIG. 2W, the terminal may include a transceiver 2 w-0, aterminal controller 2 w-i, and a storage unit 2 w-2. In the presentdisclosure, the terminal controller 2 w-1 may be defined as a circuit oran application specific integrated circuit or at least one processor.

The transceiver 2 w-0 may transmit/receive a signal to/from othernetwork entities. The transceiver 2 w-0 may receive, for example, theinformation on the beam reciprocity (beam correspondence) from the basestation and transmit the RACH signal.

The terminal controller 2 w-1 may control the overall operation of theterminal according to the embodiment of the present disclosure. Forexample, the terminal controller 2 w-1 may control the signal flowbetween the respective blocks to perform the operations according to theabove-described drawings and flowcharts. Specifically, the terminalcontroller 2 w-1 is operated according to a control signal from the basestation and may perform a control to receive the information on the beamreciprocity (beam correspondence) from the base station and transmit theRACH signal to the base station.

The storage unit 2 w-2 may store at least one of the informationtransmitted/received through the transceiver 2 w-0 and the informationgenerated through the terminal controller 2 w-1.

FIG. 2X illustrates the configuration of the base station according tothe embodiment of the present embodiment.

Referring to FIG. 2X, the base station may include a transceiver 2 x-0,a base station controller 2 x-1, and a storage unit 2 x-2. In thepresent disclosure, the base station controller 2 x-1 may be defined asa circuit or an application specific integrated circuit or at least oneprocessor.

The transceiver 2 x-0 may transmit/receive a signal to/from othernetwork entities. The transceiver 2 x-0 may notify, for example, theterminal of the beam reciprocity (beam correspondence), and may transmitthe related parameters together.

The base station controller 2 x-1 may control the overall operation ofthe base station according to the embodiment of the present disclosure.For example, the terminal controller 2 x-1 may control the signal flowbetween the respective blocks to perform the operations according to theabove-described drawings and flowcharts. Specifically, the base stationcontroller 2 x-1 may perform a control to transmit the information onthe beam reciprocity (beam correspondence) to the terminal, transmit therelated parameters, and receive the RACH signal from the terminal.

The storage unit 2 x-2 may store at least one of the informationtransmitted/received through the transceiver 2 x-0 and the informationgenerated through the terminal controller 2 x-1.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising: receiving, from a basestation, a master information block (MIB) on a physical broadcastchannel (PBCH), the MIB including information on a first subcarrierspacing; receiving, from the base station, a system information block(SIB) based on the first subcarrier spacing, the SIB includinginformation on a second subcarrier spacing and a third subcarrierspacing; transmitting, to the base station, a random access preamblebased on the second subcarrier spacing; receiving, from the basestation, a random access response based on the first subcarrier spacing;transmitting, to the base station, a physical uplink shared channel(PUSCH) transmission scheduled by the random access response based onthe third subcarrier spacing; and receiving, from the base station, aphysical downlink shared channel (PDSCH) transmission as a response tothe PUSCH transmission, based on the first subcarrier spacing, whereinthe first subcarrier spacing, the second subcarrier spacing, and thethird subcarrier spacing have a same subcarrier spacing value, orwherein at least some of the first subcarrier spacing, the secondsubcarrier spacing, and the third subcarrier spacing have differentsubcarrier spacing values.
 2. The method of claim 1, further comprisingreceiving, from the base station, a primary synchronization signal (PSS)and a secondary synchronization signal (SSS), wherein a subcarrierspacing used for receiving of the PSS and the SSS is identified based ona frequency band on which the PSS and the SSS are received.
 3. Themethod of claim 2, wherein each of the PSS, the SSS and the MIB isreceived on a frequency position with an offset from a center frequency.4. The method of claim 1, wherein the PUSCH transmission includes amessage 3 (MSG3) of a random access procedure.
 5. The method of claim 1,wherein the PDSCH transmission includes a user equipment (UE) contentionresolution identity.
 6. A method performed by a base station in awireless communication system, the method comprising: transmitting, to aterminal, a master information block (MIB) on a physical broadcastchannel (PBCH), the MIB including information on a first subcarrierspacing; transmitting, to the terminal, a system information block (SIB)based on the first subcarrier spacing, the SIB including information ona second subcarrier spacing and a third subcarrier spacing; receiving,from the terminal, a random access preamble based on the secondsubcarrier spacing; transmitting, to the terminal, a random accessresponse based on the first subcarrier spacing; receiving, from theterminal, a physical uplink shared channel (PUSCH) transmissionscheduled by the random access response based on the third subcarrierspacing; and transmitting, to the terminal, a physical downlink sharedchannel (PDSCH) transmission as a response to the PUSCH transmission,based on the first subcarrier spacing, wherein the first subcarrierspacing, the second subcarrier spacing, and the third subcarrier spacinghave a same subcarrier spacing value, or wherein at least some of thefirst subcarrier spacing, the second subcarrier spacing, and the thirdsubcarrier spacing have different subcarrier spacing values.
 7. Themethod of claim 6, further comprising transmitting, to the terminal, aprimary synchronization signal (PSS) and a secondary synchronizationsignal (SSS), wherein a subcarrier spacing used for transmitting of thePSS and the SSS is identified based on a frequency band on which the PSSand the SSS are transmitted.
 8. The method of claim 7, wherein each ofthe PSS, the SSS and the MIB is transmitted on a frequency position withan offset from a center frequency.
 9. The method of claim 6, wherein thePUSCH transmission includes a message 3 (MSG3) of a random accessprocedure.
 10. The method of claim 6, wherein the PDSCH transmissionincludes a user equipment (UE) contention resolution identity.
 11. Aterminal in a wireless communication system, the terminal comprising: atransceiver configured to transmit and receive a signal; and acontroller coupled with the transceiver and configured to: receive, froma base station, a master information block (MIB) on a physical broadcastchannel (PBCH), the MIB including information on a first subcarrierspacing, receive, from the base station, a system information block(SIB) based on the first subcarrier spacing, the SIB includinginformation on a second subcarrier spacing and a third subcarrierspacing, transmit, to the base station, a random access preamble basedon the second subcarrier spacing, receive, from the base station, arandom access response based on the first subcarrier spacing, transmit,to the base station, a physical uplink shared channel (PUSCH)transmission scheduled by the random access response based on the thirdsubcarrier spacing, and receive, from the base station, a physicaldownlink shared channel (PDSCH) transmission as a response to the PUSCHtransmission, based on the first subcarrier spacing, wherein the firstsubcarrier spacing, the second subcarrier spacing, and the thirdsubcarrier spacing have a same subcarrier spacing value, or wherein atleast some of the first subcarrier spacing, the second subcarrierspacing, and the third subcarrier spacing have different subcarrierspacing values.
 12. The terminal of claim 11, wherein the controller isfurther configured to receive, from the base station, a primarysynchronization signal (PSS) and a secondary synchronization signal(SSS), and wherein a subcarrier spacing used for receiving of the PSSand the SSS is identified based on a frequency band on which the PSS andthe SSS are received.
 13. The terminal of claim 12, wherein each of thePSS, the SSS and the MIB is received on a frequency position with anoffset from a center frequency.
 14. The terminal of claim 11, whereinthe PUSCH transmission includes a message 3 (MSG3) of a random accessprocedure.
 15. The terminal of claim 11, wherein the PDSCH transmissionincludes a user equipment (UE) contention resolution identity.
 16. Abase station in a wireless communication system, the base stationcomprising: a transceiver configured to transmit and receive a signal;and a controller coupled with the transceiver and configured to:transmit, to a terminal, a master information block (MIB) on a physicalbroadcast channel (PBCH), the MIB including information on a firstsubcarrier spacing, transmit, to the terminal, a system informationblock (SIB) based on the first subcarrier spacing, the MIB includinginformation on a second subcarrier spacing and a third subcarrierspacing, receive, from the terminal, a random access preamble based onthe second subcarrier spacing, transmit, to the terminal, a randomaccess response based on the first subcarrier spacing, receive, from theterminal, a physical uplink shared channel (PUSCH) transmissionscheduled by the random access response based on the third subcarrierspacing, and transmit, to the terminal, a physical downlink sharedchannel (PDSCH) transmission as a response to the PUSCH transmission,based on the first subcarrier spacing, wherein the first subcarrierspacing, the second subcarrier spacing, and the third subcarrier spacinghave a same subcarrier spacing value, or wherein at least some of thefirst subcarrier spacing, the second subcarrier spacing, and the thirdsubcarrier spacing have different subcarrier spacing values.
 17. Thebase station of claim 16, wherein the controller is further configuredto transmit, to the terminal, a primary synchronization signal (PSS) anda secondary synchronization signal (SSS), and wherein a subcarrierspacing used for transmitting of the PSS and the SSS is identified basedon a frequency band on which the PSS and the SSS are transmitted. 18.The base station of claim 17, wherein each of the PSS, the SSS and theMIB is transmitted on a frequency position with an offset from a centerfrequency.
 19. The base station of claim 16, wherein the PUSCHtransmission includes a message 3 (MSG3) of a random access procedure.20. The base station of claim 16, wherein the PDSCH transmissionincludes a user equipment (UE) contention resolution identity.